Re: idle_in_transaction_timeout

Robert Haas <robertmhaas@gmail.com> writes:
> On Sun, Jun 29, 2014 at 12:32 PM, Kevin Grittner <kgrittn@ymail.com> wrote:
>> I propose to push this as it stands except for the postgres_fdw
>> part.  The default is easy enough to change if we reach consensus,
>> and expanding the scope can be a new patch in a new CF.
>> Objections?

> Yeah, I think someone should do some analysis of whether this is
> adding gettimeofday() calls, and how many, and what the performance
> implications are.

I believe that as the patch stands, we'd incur one new gettimeofday()
per query-inside-a-transaction, inside the enable_timeout_after() call.
(I think the disable_timeout() call would not result in a gettimeofday
call, since there would be no remaining live timeout events.)

We could possibly refactor enough to share the clock reading with the call
done in pgstat_report_activity.  Not sure how ugly that would be or
whether it's worth the trouble.  Note that in the not-a-transaction-block
case, we already have got two gettimeofday calls in this sequence, one in
pgstat_report_stat and one in pgstat_report_activity :-(
        regards, tom lane